Novel candidate of metal-based thermal barrier coatings: High-entropy alloy

To obtain compatible properties of low thermal conductivity and high thermal stability, Al0.6CoCrFeNiTi highentropy alloy was designed as a novel candidate of metal-based thermal barrier coatings (MBTBCs). The corresponding high-entropy alloy coatings were fabricated by both high-velocity oxygen-fuel spraying (HVOF) and atmospheric plasma spraying (APS), and then the dependence of thermal insulation properties on microstructure was investigated. The both coatings exhibit a simple body-centered cubic (BCC) structure, but present obvious difference in microstructure and defect characters which relates to the evolution of in-flight particles. Benefit from the extremely low thermal conductivity, the APS-deposited coating can increase 13.24 degrees C of the surface temperature of piston crown and yield a temperature reduction of 19.00 degrees C along the thickness direction, which mean a positivity on enhancing the power efficiency of vehicle engines without sacrificing the strength of aluminum alloy components. In virtue of a decoupling method, the crucial effect of microstructure on thermal conductivity is disclosed, thus interpreting the excellent thermal insulation property of APS-deposited coating dominated by grain refinement and disordered BCC structure. The present results demonstrate a great potential of high-entropy alloy coatings as thermal barrier application and provide an inspiration for future works aiming to design these coatings to meet specific engineering needs.

Automated summary

Al0.6CoCrFeNiTi high-entropy alloy was designed as a metal-based thermal barrier coating with low thermal conductivity and high thermal stability. The atmospheric plasma spray coating exhibited excellent thermal insulation performance, increasing the surface temperature of the piston crown while reducing the temperature along the thickness direction.